Written by Fin
I’ve always found something deeply mathematical about tarot. Not just in the way the cards interact, mirroring patterns in life, but in the numbers themselves.
The first time I realized that both the Major Arcana (22 cards) and the full deck (78 cards) are equilateral triangular numbers, it felt like unlocking a hidden layer of meaning, something structural and fundamental about The Tarot itself.
What Are Triangular Numbers?
For those who, like me, had to jog their memory about mathematics at school, a triangular number is a number that can form an equilateral triangle when represented as a stack of dots. Imagine a pyramid made of stacked pebbles — one at the top, two beneath, three beneath that, and so on. The sum of these layers forms what’s called a triangular number.
The sequence of triangular numbers begins as follows: 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78…
Each of these can be arranged into an equilateral triangle. If you add up all the numbers from 1 to 6, for example, you get 21, a perfect triangle. If you add up all the numbers from 1 to 12, you get 78. And if you go one step beyond 21? You land at 22.
The Major Arcana: The Structure of 22
The number 22 is significant in tarot because it represents the complete Fool’s Journey. The Fool begins at card 0 and progresses through 21 archetypes, completing a cycle of transformation. Mathematically, 22 is also the sum of the first 6 numbers (1+2+3+4+5+6), making it a triangular number. The connection between these numerical properties and the way the Major Arcana is structured suggests a logical foundation to its design.
The Minor Arcana and the Power of 78
When you expand the tarot to include all 78 cards — the full deck — you reach another triangular number. 78 is the sum of the first 12 numbers (1+2+3+…+12). The number 12 is commonly found in various structured systems, such as the zodiac signs, months of the year, and hours on a clock. This reinforces how the Minor Arcana, often linked to everyday experiences, fits within a larger framework.
The Mathematical Significance in Tarot
Recognizing this hidden mathematical symmetry adds another layer of depth to The Tarot system. The cards are not just a collection of symbols but are organized in a way that aligns with fundamental numerical patterns. Whether by deliberate design or coincidence, the presence of triangular numbers within a deck suggests an inherent structure that goes beyond simple randomness. This numerical consistency may help explain why the tarot has remained a structured and enduring tool for exploration.
So, the next time you use The Tarot, consider how its numerical foundation supports its structure. Understanding the mathematical patterns within tarot can provide a different perspective, reinforcing its place as an ordered system rather than just a mystical one.